1. Field of the Invention
The present invention belongs to the technical field of non-ferrous metallurgy, and particularly relates to a method for smelting magnesium quickly and continuously.
2. The Prior Arts
In 1950s, magnesium entered civilian market. Since 1960s, the application of magnesium in the civilian market and the space technology has promoted the development of the magnesium industry, and great breakthroughs in magnesium refining methods and production technologies have been made, thereby continuously improving economic efficiency. There are two main categories of magnesium smelting methods in the world: an electrolysis method and a heat reduction method. In the heat reduction method, calcined dolomite is used as raw materials, ferrosilicon is used as a reductant, and reduction is performed in high temperature and vacuum conditions so as to obtain metal magnesium. As the most important one, the Pidgeon magnesium smelting method adopts a simple technology, thereby greatly reducing the production cost and increasing the global yield of primary magnesium. The Pidgeon magnesium smelting method has the advantages of simplicity in operation, low investment cost and the like. However, because the Pidgeon magnesium smelting method needs to be performed in a high temperature and vacuum condition and adopts a labor-intensive intermittent operation, the Pidgeon magnesium smelting method has the defects of long-reduction cycle (10-12 h), low yield of metal magnesium (30 kg/reduction tank), high energy consumption and the like. In addition, since the reduction tank is used for a long time in a high temperature and high vacuum condition, the service life of the reduction tank is shortened and the production cost is increased. Furthermore, the used material namely dolomite needs to be calcined first and the ultrafine powder produced by calcination cannot be used, thereby resulting in serious waste of resources.
With regards to the defects of conventional silicothermic magnesium smelting method, such as long reduction period and high production cost, Chinese researchers broke through the existing standpoints of core equipment and key technology to sequentially develop novel magnesium smelting devices, as well as new ideas of aluminothermic and calciothermic magnesium smelting methods. For example, Chinese Patent Application No. 200710035929.8, Chinese Patent No. ZL 96247592.0 and others design induction heating magnesium smelting devices, wherein, Chinese Patent Application No. 200710035929.8 also designs a combination of multiple feeding devices and multiple magnesium steam condensing devices to achieve mechanical operations of magnesium smelting. Dehong Xia et al. study the idea of using a liquid calciothermic reduction method for magnesium smelting, and improve the level of automation operations by optimizing the operational technology conditions. Chinese Patent Application No. 200510045888.1 and Application No. 200910236975.3 develop new ideas about a novel metal thermal reduction for magnesium smelting method, while Chinese Patent Application No. 200510045888.1 studies the idea about thermite reduction magnesium smelting method which reduces reduction temperature by 50° C. and reduction time to 7-8 h. Chinese Patent Application No. 200910236975.3 studies a magnesium smelting technology using Si—Fe+Al+Ca composite reductants to reduce calcined and caustic magnesite mixtures, so that the reduction time is shortened to 5-9 h. Although the above researches to some extent improve the technical level of thermal magnesium smelting methods, they are improvements and enhancements derived from the basic idea of high temperature and vacuum conditions based on the conventional silicothermic magnesium smelting technology, which has no breakthrough from nature. Therefore, the defects of the conventional silicothermic magnesium smelting technology, such as long reduction cycle, high energy consumption, short life of the reduction tank and high production cost, are still not overcome fundamentally.